Apparatus foe catalytic conversion



30, 1950 v c. REED ETAL Re. 23,237

APPARATUS FOR CATALYTIC CONVERSION OF HYDROCARBON VAPORS Original Filed Jan. 29, 1941 Cluc/izd [@wra w/ m w {Lil w a 4 fi 1 v M T W m M y 1 W Reissued May 30, 1950 UNITED STATES PATENT OFFICE APPARATUS TOR/CATALYTIC CONVERSION OF HYDROCARBO N VAPORS Carl S. Reed,. New York, and. August. Henry Schutte, Hastingson Hudson N. Y., assignors. to The Lummus Company, New York, N. Y.,;a'

corporation of Dela ware fi' claims; (Cl. 23 -288) Matterenclosed inheavy brackets lappears inthe original,patentibut formsno part of this,

reissuerspecification; matter. printedinritalics indicates the additions made by reissue As :vapors are passed over the s rialsydeposited thereon during the-conversion re-q action. Ordinarily several duplicate catalyst, chambers are provided for continuous :conversion of-vapors;' but eachchamber has only a. limited.

on'v stream period during which it isactive after. which timethey reactivation must take. place; As the catalytic conversion is usually:

endothermic andthe reactivation exothermica temperature conditions in a particular-i'zchamberi cam-not be-kept stable, and the great heat'loss;

which takes placeor "the expensiveheat recovery; systems necessitated 2 as 1 well as the multiplicity ofgnchambersrequired: for continuous operation; haven made the useof this process ;very costly:

The :principal ,obj ect ofwour. invention 7 is to pro-' vide a ,--c1osed" cycle; catalytic-reaction system in which a powdered catalyst-is continuously passed. througira: reaction-zone in intimate suspension in: the" vapors to be, reacted and: then; after separation from' the 'vaporousreactants, con? tinuously passed through a reactivation zone and; thence'recycled for admixturewith further feeds each zone being continuously maintained" at :its optimum temperature .and pressure conditions: whereby the=initia1 -cost as-Well as the operating; cost' of "the catalytic reaction may; be reduced.

A: more: specific object of our-invention-is to provide;- an: improved control .for a continuous powdered catalyst reaction cycle'irr which the pressures'in the various'partshofathe system are independent-1y maintained by: sufiicient heads :of powdered catalyst to prevent" contamination of: vapors L or loss of reactedproductswithout "requiring complicated and expensive mechanical seals or valves;

-Further objects and advantages-of the invention will "be apparent from the following'descrip tlon'of "a preferred form of embodiment thereof taken. in connection. with the-rattached drawing, whichis a diagrammatic view-of a suitable flow sheet.-

In accordance with our invention, we: provide. a complete closed continuous cycle-procession effecting a catalytic reaction; withsar powdered catalyst and thereafter .rreactivatin r :the catalyst". and then s returning ;it .to. beradmixed swi th 1 fresh.

feed. Such: .processrhas primary valuewandwima portance in the. conversion of. hydrocarbons and. will bespecificallydescribed-in. connection there with although it. will: .beappreciated. that the" determined rate byithe conveyor It," which may have a suitable f eedingjme'ans I'I.

The conversion zone '|4"ma'y' be of any; desired and satisfactory. type but is preferably an elongated tube of'jsu'c'h'lengthand diameter asto assure a sufiicient time ofreaction, during the passage therethrough of the catalyst and vaporous reactants. Suchflzone maybe externally heated,- if found" desirable, and should be sufficiently insulated such that'thetemperature drop of the relatively hot vapors and catalyst will not be objectionable during theirpassagethe're through.

The catalyst is preferably in a powdered'fo'rm and may be ground as fine as' l00'40'0 mes'h, in" which condition'its area "of contact is far greater per pound of catalyst'tl'ian in the usual lump form. In such form',it willcommingle very well with the vapors and will assist in establishing 'a high conversion withina-sh'orttim'e or travel;

After removal from the conversion zone, the

reacted vapors and catalyst are separatedbythe'" separator IB, which maybe-of the cyclon'e ty pe; The reacted vap ors are withdrawn overhead 'from' the separator as by c'onduit 20, and "the sep'a rated catalys't' is removedthrough" the vertical conduit 222 motor '26.

I Conduit-12E connected to conduit" 2!, through" whichthe catalyst is passed' by means of a feed means 25' under control of The conduit 22 is relatively long and of such size that, if it is kept full of catalyst, there is no likelihood of any vapor loss therethrough. A powdered catalyst will settle to such an extent that it is possible to have a column of catalyst within reasonable limits of length which will have a pressure drop for small flows of vapor that will be substantially equal to the desired difierential of pressure between the separator I8 and the lower end of conduit 22. The motor 26, which removes the catalyst from the conduit 22, is operated at such a speed that the conduit 22 will be kept full of catalyst; A level control diagrammatically shown at 28 may be used for this purpose.

The catalyst which has been used in the foregoing reaction is now passed from conduit 24 into the reactivation chamber 30' together with air and flue gas from line 3|, which air serves to burn off the carbon and other catalyst-fouling contaminants. This reactivation is usually an exothermic reaction, and the chamber 30 may be suitably lined with refractory brick 32 to reduce heat loss to a minimum. Such practice assures removal of the powdered catalyst and the products of combustion, which comprise flue gases primarily, at a high temperature through conduit 33 into the flue gas separator and heat exchanger 34;

Like separator l8, separator 34 may also be of the cyclone type and has a similar function in that it separates the reactived catalyst from the vapors. The vapors (which are the products of combustion) are withdrawn through line 60, and the catalyst settles in vertical conduit 36 which is of suflicient length so that the vapors can not escape through the body of catalyst contained therein. Conduit 36 is provided with a secondary conduit or jacket 31 forming a liquid chamber 39, through which a heat exchanging medium such as water can be circulated; since the catalyst is very hot, substantial amounts of steam can be produced.

If desired; the water chamber 39 may be interconnected by the line 42 with the boiler 43, from which steam may be removed at 44. The boiler 43 is preferably provided with the downcomer 45; which is interconnected with the lower portion of the water chamber 39 by the line 4 I. Provision is made for the introduction of make-up water through the line 46.

The catalyst is maintained at the desired height in the conduit 36 so that a loss of vapor through the conduit 36 is prevented. As in the former case, this object may be accomplished by means eta, level control 48, which controls motor 49, which in turn operates the initial feed means l1. It will also be noted that the heat transfer from the extended column of hot catalyst is sufficiently great to produce a substantial quantity of steam which can be used for power purposes. The steam in turn tends to maintain a uniform temperature in conduit 36.

It will be thus seen that the system is pressure tight by virtue of the two vertical columns of catalyst which completely isolate the conversion zone and the reactivation zone from each other. Furthermore, the catalyst moves continuously first through an endothermic conversion zone and then an exothermic reactivation zone, each of which may be maintained at itsoptimum temperature and pressure. If it is desired to alter the flow of catalyst, this may be readily accomwhich the reactions are carried out. While in-one motors or by means of a variable speed drive placed between one motor and its driven feed means. Fresh catalyst may be introduced at I! and is preferably passed through a similar vertical column to automatically provide a pressure seal.

A part of the vapors removed from the sepaarator l8 after passage through the conversion zone [4 is usually recirculated, the recycle ratio being dependent upon the rate of conversion. This recirculation may be accomplished by passing a portion of the vapors from line 20 through line 53 and line 52 to the fresh feed vapor line ID.

If the vapors in line 20 carry too much catalyst in suspension, that portion not recirculated may be passed through a secondary separator 50, which may also be of the cyclone type. The small amount of catalyst separated therein may also be'recirculated with the vapors through line 52; in some cases this procedure may have a beneficial effect. Suitable dampers or valves 53a and 55 may be provided to regulate the amount of material which is recirculated past separator 50. A heater 54 may be provided to control the heat content of the recirculated vapors. Their quantity and quality may be accurately controlled by regulation of the speed of the respective motors 26 and 49 heretofore mentioned and by control of the temperature in conversion zone l4 and heater 54 and also by control of the temperature of the reactivation system. Highly accurate production control is thus obtainable at all times.

In a similar manner, a more complete separation of catalyst from the flue gases or products of combustion may be accomplished by passing the gases in line to the secondary flue gas separator 62, from which the catalyst-free flue gas.

is withdrawn through line 63 by blower 64 under control of damper E5.

The small amount of catalyst which may be separated out of the flue gases in this secondary separation may be returned to the reactivation zone through line 61. At the same time, some of the flue gas is conducted through line 68, under control of damper I0 and by means of blower H,

into line 3|, into which air is forced from supply line 12 by blower 14. A damper or valve 15 con-- trols the amount of air supplied.

I It will be appreciated that some admixture of flue gas with the air is usually desirable to con-.

trol the exothermic reaction in chamber 30 as the introduction of pure air may cause too rapid a generation of heat therein. Dampers I0 and 15 afford means for accurate adjustment.

It will be appreciated that one of the most important features of the invention is the continuity of flow of all materials, which continuity makespossible the establishment of relatively constant temperature conditions in the respective zones in zone it may be necessary to continuously add heat, it is possible in the other zone to continuously and simultaneously remove heat which can be applied to useful purposes so that the heat balance will show a minimum fluctuation of heat transfer and a minimum heat loss.

A second important feature is the flexibility of the apparatus in that, although different reaction Zones are isolated solely by the natural compact- -ness of the catalyst, it is possible to increase or decrease the rate of flow of catalyst without destroying the eflective height of catalyst in the.

column so that no mechanical seals are necestight zones. a differential of pressure either at low or high ab solute pressures-so that the-apparatus is useful for various catalytic reactions including the consversion ofhydrocarbons.

5A third feature is the simplicity of obtaining a substantial separation of, the gaseous from "the granular materials without great heat .loss and :the recirculation of the small portions of xthe catalyst incompletely removed inzthe firstsgsepa- "ration sta e without deleteri re The y tem is inexpensive and simple and has themini- .mumnumber of ope 'at-ing parts to become out of order or require adjustment.

Although we have described a preferred form of embodiment of our invention, it will be apparent that modifications-maybe made thereto; therefore, only such limitations as appear in the claims appended hereinafter should be applied.

We claim:

1. In a catalytic conversion apparatus including a conversion chamber and a catalyst-reactivation chamber, and a closed cyclic catalyst path therebetween including a vertical conduit, means for passing catalyst from one of said chambers to the upper end of said conduit, means for discharging the catalyst from the lower end of said conduit to the other of said chambers, said conduit being constructed to form a column of the received catalyst for compacting of the latter by gravity to maintain a required pressure differential between said chambers by sealing effect of the compacted catalyst, and a level control device responsive to fluctuations in the level of the catalyst [in the conduit] column to control said discharge of the catalyst from the conduit for retention of a head of catalyst sufficient for maintaining said pressure differential.

2. In a catalytic conversion apparatus including a conversion chamber and a catalyst-reactivation chamber, closed confined conduits permitting a uniform cycle of movement of catalyst between the chambers and including a vertical conduit, means for passing a catalyst from one of said chambers to the upper end of said conduit, a power driven conveyor operable for discharging the catalyst from the lower end of said conduit to the other of said chambers, said conduit being constructed to form a column of the received catalyst for compacting of the latter by gravity to maintain a required pressure differential between said chambers by sealing effect of the compacted catalyst, and means responsive to fluctuations in the level of the catalyst in said conduit to control the operation of said conveyor and thereby control said discharge for retention of a head of catalyst sufficient for maintaining said pressure differential.

3. In an apparatus for performing a vapor phase contact process and including means defining a zone for contact therein of vapor with a solid contact material in a finely divided state, a closed connection for passing said material between said zone and another zone and maintaining a required pressure differential between said zones, comprising a vertical conduit, delivery means for passing said material in suspension within a gaseous medium from one of said zones to the upper end of said conduit, means at the juncture of said delivery means and said conduit to separate the contact material from the gaseous medium for gravitation of the separated contact material freely into the conduit, means to conduct the separated gaseous medium from the upper end of said conduit, a power-driven conveyor operable for discharge of said material from the lower end of said conduit to the other of said zones, said conduit beingconstructed and arrangedto-forma packed mass column-of the received material for compacting of 1 the latter by gravity to maintain ftherequired pressure differential vby sealing effect of the compacted material andsaid conveyor being in constantly open re* ceiving communication withthe-eonduit-andbeing constructed and arranged to free the-material receivediromthe conduit'from the-pressure of said column, and means responsive to fluctuations in height ofsaid'packed mass column and operable to control operation-cf said conveyor tothereby control saiddischarge-for retention of ahead of said material within the *conduit sufficiehtto maintainsaid pressure differential.

4. In an apparatus for performing a vapor ase. sontas rprocess and including means finingazone forcontact therein of vapor with a solid contactlmaterial.inafinely divided state, and means defining a' zonefor reactivation therein rof said contact material, a closed connection for passing said: material from said :contact :zone to said reactivation zone, and a closed connection for passing the reactivated material from the reactivation zone to the contact zone for reuse therein whereby a uniform cycle of movement of catalyst is established, each of said connections comprising a vertical conduit, means for passing the material from one of said zones to the upper end of said conduit in the connection to the other of said zones, a power driven conveyor operable for discharging the material from the lower end of said conduit to the other of said zones, said conduit of each of said connections being constructed and arranged to form a packed mass column of the received material for compacting of the latter by gravity to maintain a superatmospheric pressure difierential between said zones by sealing effect of the compacted material and each of said conveyors being in constantly open receiving communication with its respective conduit and being constructed and arranged to free the material received from the conduit from the pressure of the column, and means responsive to fluctuations in height of said packed mass column and operable to control the operation of the discharge conveyors of the conduits of said connections individually to thereby control the discharge from each conduit for retention of a head of the material within the conduit sufiicient for maintaining said pressure differential.

5. In a. catalytic conversion apparatus including a. conversion chamber and a catalyst-reactivation chamber, and means forming a closed cyclic catalyst circuit therebetween including a vertical path as a. substantialportion thereof, means for passing catalyst from one of said chambers to the upper end of said vertical path, means for (L0- cumulating and discharging the catalyst from the lower end of said vertical path to the other of said chambers, said vertical path portion being constructed to form a column of the received catalyst for compacting of the latter by gravity to maintain a required pressure differential between said chambers by sealing efiect of the compacted catalyst, and a level control device connected to said path and said accumulating and discharging means responsive to fluctuations in height of said gravity compacted column to control said discharge of the catalyst from the vertical path.

6. In a catalytic conversion apparatus including a conversion chamber and a catalyst-reactivation chamber, and a. closed cyclic catalyst path therebetween, a vertical portion thereof including a conduit, and upstanding receiving means for passing catalyst from said conversion cham: ber to the upper end of said conduit, means for accumulating and discharging the catalyst from the lower end of said conduit to said catalyst reactivation chamber, said upstanding means and said conduit being constructed to form a column of the received catalyst for compacting of the latter by gravity to maintain a required pressure difierential between said chambers by sealing eiject of the compacted catalyst, and a level control device connected to said upstanding means andsaid accumulating and discharging means responsive to fluctuations in the level of the catalyst column to control said discharge of the catalyst from the conduit.

CARL S. REED.

AUGUST HENRY SCHUTTE.

REFERENCES CITED The following references are of record in the file of this patent or the original patent:

UNITED STATES PATENTS Number Number 15 533,037 

